Recently, information terminal equipment including a personal computer and a server, and communications equipment such as an internet router and optical communication have been required to process high-volume information at a high speed, and the increases in speed and frequency of an electronic component have been made. In accordance with such increases, printed-wiring boards for use in such communications equipment have been demanded for having enhanced electrical characteristics in order to cope with a high frequency, and in particular, demanded for having a low dielectric constant and a low dielectric tangent.
As a material for printed-wiring boards excellent in dielectric characteristics, for example, a resin composition containing a bifunctional phenylene ether resin of a specific structure, a thermosetting resin, and a curing agent for the thermosetting resin is known (for example, see Patent Literature 1).
Printed-wiring boards are usually produced using a metal foil-clad laminate or the like produced by laminating with copper foil or the like a prepreg that is in the semi-cured state of a thermosetting resin composition, and pressurizing and heating the resulting laminated body. Therefore, the prepreg itself is demanded for having fluidity (flowing characteristics) at the time of pressurizing and heating (at the time of forming) at the time of production of a laminate, from the viewpoint of adhesion strength at the time of laminating.
When a polyphenylene ether resin is used as a resin component of the prepreg, the resin has a high molecular weight per unit structure, has a high viscosity (melt viscosity) when being applied heat to be molten, and thus has suffered from such a problem that flowing characteristics at the time of production of a laminate are insufficient.
In order to solve this problem, the present applicants have already reported a resin composition including a specific bifunctional phenylene ether oligomer, a naphthol aralkyl-based cyanate ester compound, a bisphenol A-based cyanate ester compound, a brominated flame retardant and an inorganic filler (for example, see Patent Literature 2).